Transcriptome and Proteome Analysis Revealed the Influence of High-Molecular-Weight Glutenin Subunits (HMW-GSs) Deficiency on Expression of Storage Substances and the Potential Regulatory Mechanism of HMW-GSs

Abstract

The processing quality of wheat is affected by seed storage substances, such as protein and starch. High-molecular-weight glutenin subunits (HMW-GSs) are the major components of wheat seed storage proteins (SSPs); they are also key determinators of wheat end-use quality. However, the effects of HMW-GSs absence on the expression of other storage substances and the regulation mechanism of HMW-GSs are still limited. Previously, a wheat transgenic line LH-11 with complete deletions of HMW-GSs was obtained through introducing an exogenous gene Glu-1E^bx to the wild-type cultivar Bobwhite by transgenic approach. In this study, comparative seed transcriptomics and proteomics of transgenic and non-transgenic lines at different seed developmental stages were carried out to explore the changes in genes and proteins and the underlying regulatory mechanism. Results revealed that a number of genes, including genes related to SSPs, carbohydrates metabolism, amino acids metabolism, transcription, translation, and protein process were differentially enriched. Seed storage proteins displayed differential expression patterns between the transgenic and non-transgenic line, a major rise in the expression levels of gliadins were observed at 21 and 28 days post anthesis (DPA) in the transgenic line. Changes in expressions of low-molecular-weight glutenins (LMW-GSs), avenin-like proteins (ALPs), lipid transfer proteins (LTPs), and protease inhibitors (PIs) were also observed. In addition, genes related to carbohydrate metabolism were differentially expressed, which probably leads to a difference in starch component and deposition. A list of gene categories participating in the accumulation of SSPs was proposed according to the transcriptome and proteome data. Six genes from the MYB and eight genes from the NAC transcription families are likely important regulators of HMW-GSs accumulation. This study will provide data support for understanding the regulatory network of wheat storage substances. The screened candidate genes can lay a foundation for further research on the regulation mechanism of HMW-GSs.

Keywords: HMW-GSs; candidate genes; regulation mechanism; seed storage substances; wheat.

Figure 1

GO and KEGG enrichment results. (a) GO enrichment results from both transcriptomic and proteomic data at 21 DPA. (b) KEGG enrichment results at 21 DPA from the transcriptomic data. (c) KEGG enrichment results at 7, 14, 21, and 28 DPA from the proteomic data.

Figure 1

GO and KEGG enrichment results. (a) GO enrichment results from both transcriptomic and proteomic data at 21 DPA. (b) KEGG enrichment results at 21 DPA from the transcriptomic data. (c) KEGG enrichment results at 7, 14, 21, and 28 DPA from the proteomic data.

Figure 2

Composition of differentially expressed SSPs and expression patterns of different types of SSPs. (a) Composition of differentially expressed SSPs; (b) Venn diagram of differentially expressed SSPs at different seed developmental stages.

Figure 3

Relative expression of key genes at four seed developmental stages. Blue bar represents the wildtype (WT), red bar represents LH-11; expression level of WT was standardized at each stage to display a clear comparison with LH-11.

Figure 4

Important genes and proteins participated in the deposition of SSPs.